Wood trim system

ABSTRACT

For attaching wood trim around a door or window frame. In the disclosed system, plastic spline-clips attached to the jambs serve to fix the jamb to the wall. The spline-clips have two splines, which engage slots in the wood trim, forming a dovetail connection between the trim and the splines. The splines are elastic enough to deflect apart to admit the trim, and then spring back to grip the trim and to push the trim tightly against the wall. Grooves cut in the edge faces of the jambs receive lugs on the clips, by which the clips are accurately positioned on the jambs. Also disclosed is a split-jamb system, in which the inside jamb-frame is positioned first, then squared up in the wall opening, and then held in place on the wall by means of with its inside spline-clips; the outside jamb-frame is then assembled to the inside jamb-frame, and the outside jamb-frame locked in place with its outside spline-clips. Also disclosed is a corner-cover, which masks the ends of converging baseboards and other trim, on both inside corners and outside corners. The corner-cover avoids the need for mitring the baseboards. The corner-cover is profiled to fit the profile of the baseboard. Also disclosed is a system for attaching trim, e.g baseboards, chair rails, to a wall. This includes a hook-clip, the hook of which engages a slot cut in the trim. The hook is springy, and presses the trim against the wall. The system biases the trim so that it is the top of the trim that is pressed against the wall.

This invention relates to trim, especially wood trim, of the kind asused in houses for finishing the edges and frames of doors and windows,chair rails, baseboards or skirting-boards, framing around panelling,and the like.

Examples will now be described with reference to the accompanyingdrawings, in which:

FIG. 1 is a cross-sectional plan view of part of an opening in a wall,of a doorframe secured into that opening, and of a wood trim attachmentsystem for use therewith.

FIG. 2 is the same view as FIG. 1, showing another trim attachmentsystem.

FIG. 3 is a cross-sectional plan view of a whole doorframe, and opening,having the trim attachment system of FIG. 2, shown during a stage ofassembly.

FIG. 4 is the same view as FIG. 3, but shows an alternative manner ofassembly.

FIG. 5 is the same view as FIGS. 3,4 and shows the completed assembly.

FIG. 6 is a similar view to FIG. 5, but shows an another trim attachmentsystem.

FIG. 7 is a view like FIG. 6, but shows the components partly assembled.

FIG. 7 a is a partly-exploded view of the components of the trimattachment system of FIG. 5.

FIG. 8 is a view like FIG. 7 a of another trim attachment system.

FIG. 9 is pictorial view of a jamb-piece component of the system of FIG.8, shown with spline-clip components attached.

FIG. 10 is a view like FIG. 8 of another trim attachment system.

FIG. 11 is a view of a corner of a room, in which two convergingbaseboards have been attached to the walls.

FIG. 12 is the same view as FIG. 11, except that a cover has been placedover the convergence of the baseboards.

FIG. 13 is the same view of the cover itself.

FIG. 14 is a view of the reverse or back side of the cover.

FIG. 15 is a plan view of the cover.

FIG. 16 is a side elevation of the cover.

FIG. 16 a is a side elevation of part of another cover.

FIG. 17 is a plan view of two baseboards converging on a corner of aroom.

FIG. 18 is the same view as FIG. 17, except that a corner-cover has beenplaced over the convergence of the baseboards.

FIG. 19 is a side elevation of another corner-cover, placed overbaseboards in a corner of a room.

FIG. 19 a is a close-up of an area of FIG. 19.

FIG. 20 is a view of an external corner of a room, in which acorner-cover has been placed over two converging baseboards.

FIG. 21 is a sectioned elevation of the foot of a wall and the floor ofa house, showing a baseboard attached to the wall by a hook-clip system.

FIG. 22 is a close-up of part of the view of FIG. 1.

FIG. 22 a is the same view as FIG. 22 of a component of the system.

FIG. 22 b is the same view as FIG. 22 of another component of thesystem.

FIG. 23 is a similar view to FIG. 21 of another hook-clip system.

FIG. 24 is a pictorial view of hook-clips being installed on a wall.

FIG. 25 is an elevation of a chair rail attached to a wall using ahook-clip system.

FIG. 26 is the same view as FIG. 12, but shows a corner-cover in usewith baseboards that have been attached by means of the system shown inFIG. 21.

The apparatuses and procedures shown in the accompanying drawings anddescribed below are examples. The scope of the patent protection soughtis defined by the accompanying claims, and not necessarily by specificfeatures of the examples.

In this description, some of the components in the drawings have beengiven numerals with letter suffixes. The same numeral without the suffixis used to indicate the component generically.

FIG. 1 shows a basic installation, which makes use of some of theinnovations described herein.

A door opening in a wall 21 includes a conventional upright two-by-fourdoorframe stud 23, to which sections of conventional drywall orplasterboard 25 are attached. A door jamb 27 fits across the width ofthe wall. Apart from its function as a component of the doorway, thejamb 27 serves to hide the unsightly stud 23, and to hide the cut endsof the plasterboards 25.

The jamb 27 has a surface 29 which, being visible, should be finished ina suitable manner, using e.g stain, varnish, paint, etc. The jamb 27 maybe of a solid decorative wood, such as oak, or may be e.g fibre board,or solid particle board, to which a decorative veneer might be appliedat least to the visible surface 29. The system as described hereinapplies when the jamb is made from other wood-based materials, or evenfrom (e.g recycled) plastic materials. It is also known to make doorjambs from bent/folded sheet metal, and the system is applicable in thatcase too, provided provision can be made for attaching the clip to thejamb.

The jamb 27 is supported and secured with respect to the wall 21 bymeans of spline-clips 30 i,30 o (collectively 30). The spline-clips 30are formed as plastic extrusions, having an extruded profile as shown inFIG. 1. The profile of the spline-clip includes a web 32, whichstraddles across the gap between the edge 34 of the jamb 27 and thesurface of the plasterboard 25 of the wall 21. A lug 36 protrudes fromthe web 32, and serves as a location stop, enabling the spline-clip 30to be positioned correctly with respect to the jamb 27. A jamb-staple 38is used to attach the spline-clip 30 immovably to the jamb 27. Awall-staple 40 is used, likewise, to attach the spline-clip 30 to thewall 21. With the inside and outside spline-clips 30 i,30 o bridgingtheir respective gaps between the jamb 27 and the wall 21, it will beunderstood that the inside and outside spline-clips 30 i,30 o, whenstapled in place, serve to hold the jamb 27 immovably with respect tothe wall 21.

To install the assembly as shown in FIG. 1, the following steps can beperformed. First, the door 41 is fixed into the assembled doorframe ofwhich the jamb 27 is a component. (Often, the door, when purchased, isalready factory-assembled into the doorframe.) The door and doorframesub-assembly is then presented into the opening in the wall 21. Theoutside spline-clips 30 o are stapled to the jamb 27, but are not yetstapled to the wall 21. The outside spline-clips 30 o are spaced oneevery forty or fifty cm, for example, over the heights of both the leftand right sides of the door, and across the lintel. (Herein, thefasteners are described as staples, and that is the preferred choice.However, nails etc, and even screws, could be used.)

When all the outside spline-clips 30 o are properly stapled to the jamb27, now the installer makes a final check as to the positions of thedoor jambs and lintel. When they are square and true, within the dooropening, now the wall staples 40 can be applied. Now, the doorframestands secured, square and true, at least as to its outside, to the wall21. It is usually possible for a reasonably skilled installer to performthe task, without assistance, of securing a door and doorframe into thewall opening, with a perfectly acceptable degree of accuracy, in just aminute or two.

It cannot be ruled out that an installer might leave the jambs not quitevertical, or otherwise not perform the door installation properly—but,so long as the installer is not over-casual, and has the right tools todo the job, the installer can leave every door they install square andtrue, repeatably, in very short order, by the use of the spline-clips inthe manner as described.

The same steps can now be performed with respect to the other side (theinside) of the door. That is to say, the inside spline-clips 30 i arenow stapled to the inside edge 34 i of the jamb 27. Again, the lug 36 isused to position the clip correctly with respect to the jamb. With allthe spline-clips 30 i attached to the jamb 27, and with the installerchecking once again, now from the inside, that everything is square andtrue, the spline-clips 30 i can be stapled to the wall.

Now, as shown in FIG. 1, the jamb 27 is secured to the wall 21, bothinside and outside, by means of the stapled spline-clips 30, and is heldin place very rigidly and securely—as of course it is required to be,since the jamb 27 provides all the support for the door 41 and itsoperational movements.

The task of squaring up the door and doorframe within the door openingin the wall is thus accomplished very quickly and easily. And theinstaller, with a minimum of skill and attention, has been able toensure that the installation is square and true. The installerpreferably should pre-attach the outside spline-clips 30 o to the jamb27, but should not pre-attach the inside spline-clips 30 i (or viceversa, if the door is to be installed from the inside). It would beimpossible (or at least very awkward) to assemble the door and frameinto the opening in the wall if both the inside and the outsidespline-clips were pre-attached.

Now, with the installation of the spline-clips 30 finished, theinstaller can turn to assembling the wood trim. The trim 43 is formedwith a profile as shown in FIG. 1, having two sloping slots, and themiddle cut away to accommodate the web of the clip. As shown in respectof the inside of the door, in FIG. 1, the jamb-spline-slot 43 of thewood trim is placed over the jamb-spline 47 of the spline-clip 30.

At the other end of the wood trim 43, the wall-spline 49 of thespline-clip 30 is snagged on the entry to the wall-spline slot 50 of thewood trim 43. Now, if the installer pushes the wood trim 43 towards thewall 21, the entry-chamfer 52 on the end of the wall-spline 49 directsthe wall-spline 49 to bend (leftwards, in FIG. 1), thereby enabling thewall-spline 49 to enter the wall-spline-slot 50. Thus, installation ofthe wood trim is a simple two-step operation for the installer; first,the wood trim is positioned so the jamb-spline 47 is entered into thejamb-spline-slot 45; then, the installer simply taps or strikes the woodtrim 43 towards the wall, by hand, whereby the wall-spline 49 enters thewall-spline-slot 50.

It will be understood that the two jamb pieces and the lintel that makeup the doorframe are manufactured in-factory, and are accurately cut andfinished. (The bottom ends of the left and right jambs might have to betrimmed by the installer in some cases, but that is a task that requiresvery little skill and attention from the installer.) Equally, the woodtrim pieces 43 are factory-cut and finished, including the mitresthereof, whereby again no craft-type skill is required on the part ofthe installer.

It will be understood also that no nails or other fasteners are requiredin respect of the wood trim pieces themselves. The wood trim can bequickly and accurately installed by a non-skilled person. There is noneed for patching or other remediation, such as filling, sanding,painting, etc, of any kind, to be done after installation. All requiredfinishing of the trim can be done in-factory—although it is not ruledout, of course, that painting etc might be done after installation. Itwill also be noted that the trim can be removed, in the future, ifdesired, and then re-fitted, all by hand, in order to facilitate thetask of painting, for example, or applying wallpaper to, the walls.

Many home-owners want to make use of a decorative hardwood, not only forthe trim 43, but also for the jambs 27 and lintel. To cater for suchcustomers, the jamb and lintels, together with the required six piecesof wood trim 43 (two upright-pieces and one cross-piece, both inside andoutside the door) and the associated spline-clips 30, may be done up forsale as a kit. It is also helpful for customers to be able to purchase aset of the three pieces of wood trim, and an appropriate set ofspline-clips, as required to trim one side of a door. The pieces againare factory-made and finished (including mitred corners).

The door itself might or might not be included in a kit. It is customaryfor doors to be manufactured to very tight tolerances as to dimensions,squareness, and so on. This fact means that it is possible to sell thekits containing the jambs, trim, etc, separately from the doors, knowingthat the kit will be bound to accurately fit any door of the nominalsize for which it has been prepared. Thus, the designer really canarrange for the wood trim pieces, in the kit, to be mitred in-factory,whereby the mitres can be done perfectly accurately, and completelyfinished, before being added to the kit. This leaves the installer withthe task of simply pressing the wood trim pieces into place, and the jobis finished.

In the above-described cases, the system of spline-clips and trim can infact be used with already existing doors and jambs. Thus, a kitcomprising just the (pre-mitred and pre-finished) wood trim, without thejambs and lintel, may be offered for sale.

The following variant requires that the spline-clips be secured to theedges of the jamb using a groove in the jamb. As such, the followingvariant system cannot be used with jambs that have not been suitablygrooved.

FIG. 2 shows another finished installation. Here, the spline-clip 60 hasa barbed lug 61, which enters the prepared groove 63 in the edge 65 ofthe jamb 67. The groove 63 is a tight fit over the barbed lug 61,whereby no staples or other fasteners are needed in order to secure thespline-clip 60 to the jamb 67.

Now, the installer lines up the door and doorframe with the opening inthe wall, and, when all is square and true, staples the spline-clips 60to the wall in the manner as previously described with reference toFIG. 1. It will be appreciated that, when the jamb 67 is secured byseveral of the spline-clips 60, the jamb 67 is now held with respect tothe wall 21 no less securely and rigidly in FIG. 2 than was the case inFIG. 1.

FIGS. 3,4,5 show the preliminary stages of the assembly. In FIG. 3, theleft and right outside spline-clips 60 o 1,60 or have been inserted intothe respective grooves 63 in the edges 65 of the jambs 67, and now theoutside spline-clips 60 ol,60 or are being stapled to the wall. The leftand right inside spline-clips 60 il,60 ir have not been inserted intotheir respective grooves during this phase, to enable the door anddoorframe sub-assembly to be inserted into the opening, from theoutside. Once the outside clips 60 o have been stapled to the wall, nowthe inside clips 60 i can be placed and tapped into their respectivegrooves 63, and stapled to the wall, in turn.

FIG. 4 shows a somewhat different manner of inserting the door anddoorframe sub-assembly into the opening. Here, the inside and outsidespline-clips 60 oh,60 ih at the hinge end of the door are insertedfirst. Now, it is a little more awkward to manoeuvre the door anddoorframe sub-assembly into the opening, but it usually can be done.Once the inside and outside hinge end clips 60 oh,60 ih have beenstapled to the wall, now the inside and outside clips at the handle endof the door can be inserted into their grooves, and stapled, in turn, tothe wall.

FIG. 5 shows the finished assembly, arising from both the FIG. 3 and theFIG. 4 cases.

Whether the installer chooses to go with (preferred) FIG. 3 or the FIG.4 installation sequence, the point is that the system of spline-clips asdescribed is versatile enough to cope with both, and still yield aninstallation in which the door is secured perfectly adequately from thestrength and rigidity standpoints, and perfectly adequately also fromthe accuracy of squareness standpoint, and yet the installation stillrequires only a minimal degree of skill and attention, and time, fromthe installer. This is even more true of the barbed lug 61 and groove 63arrangement of FIGS. 3,4,5 than of the plain location lug 36 arrangementof FIG. 1. Once both the inside and the outside spline-clips are stapledto the wall, there is no tendency for the barbed lugs 61 to work loosefrom the grooves 63, even over many years of service. Of course, if thedoor were to be abused, e.g by repeated heavy slamming, no doubt somefailure or partial failure might occur—but that is true of any doorinstallation.

It is traditional for installers to insert tapered shims between thedoor jamb and the wall stud, whereby the jamb can be held solidly andsecurely with respect to the wall. An aspect of the installerstraditional skill has been the art of selecting and placing suitableshims, within the very short time which is all that can be economicallyallocated for the task. If the installers have not got the shims quiteright, in that allocated time, they tend to move on anyway to the nextdoor installation, and poor door jamb shimming is all too common a faultin the building trade.

It will be understood that the system of spline-clips, as describedherein, can do away with the need for shims and shimming, in many cases,and still the door jamb is secured to the wall just as, if not more,securely and rigidly than when shims were used. There is a shorter timeper installation, and the installations are more nearly perfect, moreoften. In some jurisdictions, the provision of shims in door jambs is acode requirement, and in that case, the installer should of courseprovide them.

The spline-clips system, as described, does not preclude the use ofshims. In fact, the use of the spline-clips system makes the task ofshimming easier, in that the shims can be inserted after the door jambshave been secured to the wall. When using the spline-clips system, asdescribed, some installers prefer to add shims at critical points, e.garound the door hinges and at the latch and at or near the mitredjoints. Thus, the installer might shim above and below the hinge area.

Indeed, door installers often prefer to provide a shim actually behindthe hinge, and then run a long screw through one of the hingescrew-holes, right through the jamb, the shim, and into the door stud23. This measure couples the strength and rigidity of the stud to thatof the jamb, at the critical points. If the installer were to insertsuch a long screw without shimming, that might cause the jamb todistort, and shimming is therefore recommended for the through-screwcase. Again, the fact that the jambs (and the whole doorframe) arealready fixed in place, as a result of using the spline-clips system,means that the shimming task is not even slightly onerous orskill-demanding. Of course, if shims are to be inserted, that must bedone when the trim is not present.

In the further variant as shown in FIGS. 6,7,7 a the jambs are each intwo pieces. The completed split-jamb arrangement is shown in FIG. 6. Thetwo pieces of the split-jamb may be termed the door piece or outsidepiece 70, and the inside piece 72. Both left and right jambs, and thelintel, are split in this way.

The outside and inside jamb pieces 70,72 are held together with a key74, and the grooves 76 that receive the key correspond to the grooves 63in the edges of the jambs that receive the barbed lugs 61 of thespline-clips 60. That is to say, the outside jamb pieces can bereversed, in that both edges of the outside jamb pieces are equallygrooved. Likewise, the inside jamb pieces. This can be advantageous whenit comes to a choice of fitting the door with the hinge end either tothe left or to the right. The hinges, and the latch socket, can be builtone into the left, and the other into the right, outside pieces of thejamb, which can easily be switched around if need be.

One of the benefits of the split-jamb arrangement is that it permits thespline-clips to be pre-assembled, in the factory, to all the jambpieces. Indeed, the clips can be permanently secured into the grooves inthe jamb pieces, in-factory, e.g with adhesive. (Of course, the woodtrim 78 is kept separate (i.e is not pre-assembled), and is onlyassembled and tapped onto the spline-clips 60 once the clips have beenstapled to the wall.)

There is an argument against pre-attaching the spline-clips to thejambs, which is that the resulting sub-assembly is of a form that mightmake it vulnerable to being damaged during shipping. For those who wishto avoid this danger, and ship the jambs and spline-clips separately, itis an advantageous aspect of the spline-clip system that thespline-clips are so easily assembled to the jambs by the installer, onthe job—and not only easily, but in a manner whereby even an ineptinstaller can hardly misplace or misalign the spline-clips on the jambs.Also for those who fear damage to the jambs during transit, the presenceof the slots in the edges of the jambs means that suitable protectorscan be easily fixed over the edges of the jambs.

FIG. 7 shows the first phase of assembly of the door and doorframesub-assembly into the door opening in the wall. As before, an installerwith little skill, and not much attention, can staple the door anddoorframe sub-assembly into the opening, leaving the assembly square andtrue, more or less perfectly every time. It is a simple matter also forthe installer then to assemble the inside pieces of the jambs, andstaple their respective spline-clips also to the wall, to give theresult as shown in FIG. 6.

FIG. 7 a shows a close-up of some of the components, and illustrates theassembly stages.

As mentioned, the split-jambs variant is advantageous because it enablesall the spline-clips to be glued into, or to be otherwise pre-assembledto, their respective jamb-pieces, while enabling the two pieces of thejamb to be assembled into the opening in the wall from opposite sides ofthe wall.

The split-jamb variant is advantageous also because it accommodateswalls of different thickness. Generally, in the case of a wall made fromplasterboard panels secured over studs, the two opposite surfaces ofwall are, for practical purposes, perfectly parallel. Thus, thethickness of the finished wall, around the door opening, is the sameover the whole area of the wall surrounding the opening.

However, even though a given wall is (usually) consistent as tothickness, it does not follow that all walls, though made to the samenominal dimensions, have exactly the same thickness. Thus, jambs (andlintels) made in-factory to the nominal thickness, do not always exactlyfit the actual wall. The split-jamb variant readily accommodates itselfto walls that differ slightly in thickness.

The split-jamb variant, however, does not so easily accommodatevariations of thickness within one particular wall. Plasterboard wallsare commonly finished by taping over the joints and corners andnail/screw heads, and then applying filler compound to conceal the tapeand heads. When the walls have been finished in this way, it is notuncommon for there to be slight thickness variations, i.e variations inthe thickness of the grout. Usually, if a wall does vary in thickness,it does not do so in a regular manner, but rather the variations takethe form of ripples.

In one common form of thickness-variation, the wall is of uniformthickness from top to bottom, except that at the very bottom of thewall, the filler compound is slightly thicker. The split-jamb variant ofthe spline-clip system, as described herein, cannot accommodatethickness bumps and ripples, as such; but it has been found that it can,in typical cases, substantially reduce the effects of those bumps andripples, by halving, for example, the amplitude thereof.

FIG. 8 shows another variant. In FIG. 8, the extruded plasticspline-clip 80 is provided with a location-and-securement lug 81. Thedoor jamb piece 83 is also provided with a location-and-securementgroove 85. A toe 87 on the end of the lug 81 engages the groove 85. Topermit assembly to the jamb piece, a spline-clip profiled as in FIG. 8of course has to be distorted. (It might be possible to slide the clipslengthwise along the jamb pieces, but that is not preferred as they are(or they should be) a tight fit.) It is simple enough for the designerto provide that the distortion is small enough not to damage the clip,and yet is sufficient, once the toe 87 is in the groove 81, to renderthe spline-clip more or less completely permanently locked,mechanically, to the jamb piece 83—and to remain so even if the doorwere to be repeatedly and abusively slammed.

The use of a location-and-securement lug and groove, as in FIG. 8, ispreferred for use with split-jambs, because, with split-jambs, thespline-clips 80 can be pre-attached to the jambs 83 in-factory, when itcan be assured that the required distortions do not damage the clips (orthe jambs). If the assembly of the spline-clips to the jambs is left tothe installer, that task might be too troublesome and demanding,especially given the simplicity and foolproof ease that characterisesthe system as a whole.

The door jamb piece 83 of FIG. 8 is set up with the latch socket 89, asshown. The lower location-and-securement groove 85 a is provided inorder to enable the jamb piece with the latch socket in it to bereversed. Thus, the same jamb-piece can be used whether the door is toopen on the left or on the right. The same applies to the complementaryoutside jamb-piece of the door-set, to which are attached the doorhinges.

FIG. 9 shows a length of the outside jamb 83, with some spline-clips 80pre-attached.

Another variant on the split-jamb theme is shown in FIG. 10. Here, thereis no separate key, like 74, but rather, the function attributable tothe key here is performed by a tongue 90 of the lower piece of the jamb.The doorstop is formed into the door piece 92 of the jamb.

Also shown in FIG. 10 is a variant on the manner of attaching thespline-clip 94 to the jamb. Again, a location-and-securement lug 87,with a toe 85, is fitted into a complementary groove in the jamb 92. Thespline-clip includes a platform to the right of the lug 87, which restson the edge 96 of the jamb, and serves to position and support thespline-clip with respect to the jamb. The spline-clip is secured to thejamb by means of staples 98 through the lug 87.

There is no access to the region from which the staple 98 is inserted,once the jamb has been assembled and applied to the wall, so a design inwhich a fastener passes through the lug 81 can only be used withsplit-jambs. If the jamb is in one unitary piece, at least the set ofeither the inside clips or the outside clips must be left to theinstaller to attach to the jamb, after the jamb has been positioned inthe opening—and of course the staple 98 cannot be inserted at thatstage.

The designer might wish to arrange the spline-clip to extend the fullheight of the door jamb, and the full width of the door lintel, asrespective long lengths of the spline-clip extrusion. However, it ispreferred that the spline-clips be in separate pieces, spaced some fortyor fifty cm apart, as illustrated in FIG. 9.

Each individual spline-clip should be long enough to allow ample roomfor the staples or other fasteners that will secure them to the wall.Each piece of the spline-clip preferably should be about three cm longor more (“long” being in the direction of the extrusion), and about fivecm long is preferred. Preferably, the spline-clip should be sized anddimensioned to encourage the installer to put the staples where theywill enter the studs.

As to width, door trim mouldings vary as to their width, typicallybetween about five and ten cm. The width of the spline-clip has to beless than the width of the trim, so as to leave respective engagementlands 101,103 (FIG. 7 a) at the wall end and the jamb end of the trim.Apart from that, the spline-clip preferably should be as wide as thetrim allows, for good stability and holding power.

The designer need not seek every scrap of width available, however, anda manufacturer of trim might prefer the emphasis that several differenttrim profiles all use a single spline-strip extrusion.

The designer should also see to it that the spline-clip profile is sodimensioned that the staples or other fasteners that are used to securethe trim to the wall are assured of passing into the door frame stud 23,and not into the space beyond. Securing the spline-clip to theplasterboard, rather than to the stud, is inadvisable.

The profile of the trim has to be matched to the profile of the splinestrip (or vice versa). In fact, the profile of the spline strip imposessome limitations to the flexibility of design of the profile of thetrim. Again referring to FIG. 7 a, the central area 105 of thenon-visible side of the trim has to be cut away, to provide room for theweb portion 107 of the spline-clip 60. This is not difficult; in fact,there is typically ample room for the cut away area to be large enoughfor electrical wires (e.g speaker or telephone cables) to be run alongthe length of the trim, and thus pass around a door.

Preferably, the two splines (i.e the jamb-spline and the wall-spline)are positioned right at the very ends of the spline-clip. The splines onthe spline-clip define a dovetail shape. It should be regarded that amale dovetail structure exists between the two spline slots in the woodtrim, while the two splines on the spline-clip define a female dovetailstructure.

It might be thought that it would be equivalent if the male and femaleroles were reversed; however, reversal of these roles is not preferred.If the wood trim were to form the female dovetail structure, the woodmaterial between the slots would then be subjected to tensile stresses,rather than to the preferred compressive stress, which could lead topremature failure.

There is another reason also why it is advantageous for the splines onthe spline-clip to be arranged as the female dovetail, which is that thefemale-dovetail splines, upon being urged apart by the presence of themale dovetail of the wood trim, insofar as the plastic spline-clip isflexible and capable of deflecting, tend to curl or rotate (slightly)into closer contact with the wall and with the jamb. This rotation ofthe ends of the spline-clip is desirable, because it urges a tighterdegree of contact between the engagement lands 101,103 of the wood trimto the wall and to the jamb.

The profile of the plastic spline-clip is formed by extrusion, andtherefore the designer is at liberty to call for re-entrant features, ifdesired. On the other hand, the wood trim profile is formed by cutting,using rotating saws, which practically forbids the formation ofre-entrant shapes in the profile. The dovetail format, using flat-sidedslots, is preferred because that shape enables forces to be exerted ontothe wood trim, without having to resort to re-entrant features in theprofile of the wood trim.

The flat-sided dovetail form is preferred also in that components canvary slightly dimensionally, due to tolerances, and the flat-sideddovetail form allows the springiness of the splines (or at least of thewall-spline) to maintain the force urging the wood trim against the walland jamb, even though the dimensions of the components might varyslightly.

Even so, the requirement for accurate cutting of the wood trim is ratherhigh, with the system as described herein, and the system should not beconsidered unless high tolerance standards can be assured and maintainedduring manufacture of the wood trim. However, using modern profilecutting machines, and with reasonably careful tool-setting, the requiredaccuracy can be attained with reasonable ease. The flat-sidedmale-dovetail form contributes to this ease.

For economical cutting of the wood trim profile, preferably the axes ofthe rotating saws should be all vertical. That is to say, defining thedirection of movement of the wood trim through the cutters as horizontaland north-south, the axes of all the cutters should appear to bevertical when viewed from east or west, and should all appear to beeast-west when viewed from above the table. Preferably, the axes shouldbe kept stationary, while the wood is being fed through the saws. Theslots as required in the trim, in order to make use of the spline-clipssystem, are perfectly in keeping with this preference for economicalcutting.

It is not required that the axes of the saws be all parallel when viewedfrom the north or south. Preferably, the two slots in the wood trim, asillustrated, are cut by saws the axes of which are angled mutually atthe required mutual angle of the slots.

It is not necessary, in the spline-clip system, for the slots in thewood trim to be parallel-sided, i.e for the slots to be of constantwidth along their depth. However, making the slots parallel-sided doesmake for slightly simpler tooling and preparation of the cutting saws.Also, the bottoms of the slots need not be square with sharp corners, asillustrated; the sharper the bottom corners of the slots, the more theremight be a problem of a premature crack starting at the (most stressed)corner.

The steeper the slope of the splines, the more they tend to urge theirrespective ends of the wood trim into contact with the wall and jamb. Infact, it is the slope of the wall of the slot in the wood trim, at thecontact point, that determines the force with which the trim is heldagainst the wall or jamb. The wall of the slot in the wood trim, at thepoint where contact is made between the wall and the engaging spline,lies at an angle with respect to a perpendicular to the plane of thewall. Preferably, the angle should be about ten degrees or more.

The angle AJ in respect of the jamb-spline-slot may be steeper than theangle AW in respect of the wall-spline-slot, since the jamb-spline doesnot have to deflect, or does not have to deflect as much as thewall-spline. More particularly, preferably the angle AJ should be aboutthirty degrees or more, while the angle AW preferably should be abouttwenty degrees or more.

As mentioned, the jamb-spline 49 is provided with a lead-in chamfer 52.As shown in FIG. 1, the jamb-spline 47 on the clip 30 i receives thejamb-spline-slot 45 in the trim 43. During installation of the woodtrim, it is required, as mentioned, that the wall-spline 49 should bend(i.e bend to the left in FIG. 1) when it is being is engaged by thecorner of the wall-spline-slot 50. The lead-in chamfer 52 on thewall-spline 49 should be dimensioned such that the corner of thewall-slot 50 strikes the sloping surface of the lead-in chamfer, andnot, for example, the very end of the wall-spline 49, which might causethe wall-spline simply to buckle.

There is no need for the jamb-spline, at the other end, to be formedwith a corresponding lead-in chamfer. The jamb-spline 47 on thespline-clip 30 can be entered into the jamb-spline-slot 45 in the woodtrim 43, by simple positioning of the wood trim 30 i, as shown in FIG.1, without needing the jamb-spline to bend or deflect.

Thus, the two splines perform different functions, and can be shapeddifferently to reflect this. Since the jamb-spline is not required tobend (although it is not detrimental if the jamb-spline can bendsomewhat), the jamb-spline can be short and stumpy, while thewall-spline must be flexible enough (which means long and thin enough)to deflect far enough to permit installation without damage to thewall-spline.

The different roles as described for the deflection of the jamb-spline,and the non-deflection of the wall-spline, could be reversed. That is tosay, the designer might arrange for the wood trim to be assembledwall-spline first, and then be tapped down onto the jamb-spline, ratherthan jamb-spine first, as shown.

As to both the jamb slot and the wall slot, in the wood trim, only oneside of each slot is functionally effective, being the side of the slotthat is closer to the other slot. The respective splines press againstthese functional sides of the slots, and the pressure urges the wall endof the wood trim firmly against the wall 21, and urges the jamb end ofthe wood trim firmly against the jamb 27.

The other sides of the slots in the wood trim are not contacted by theirrespective splines. In fact, the slots should be wide enough to ensurethat such contact does not happen, since contact of the spline with bothsides of the slot would probably make it impossible to assemble the woodtrim to the spline-clip. Similarly, the designer should see to it thatthe tips of the splines cannot make contact with the bottoms of theslots. Apart from that, the slots should be as narrow and as shallow aspossible, since the slots can only weaken the mechanical integrity ofthe wood trim profile.

Regarding the groove 76 (see FIG. 7 a) in the edge of the jamb,preferably the groove should be in the middle of the edge of the jamb,for strength-in-symmetry reasons. The designer should also see to itthat there is enough room for the jamb-end engagement land 103 to engagethe remaining surface of the edge to the right of the groove, and thatconsideration might lead the designer to place the groove slightly tothe left of centre of the jamb edge 34.

The groove in the edge of the jamb should preferably be parallel to theoverall width of the jamb, i.e at right angles to the edge of the jamb;if the groove were to lie at an angle, forces acting on the jamb, e.gdue to normal (and abnormal) operation of the door, might cause thebarbed lug 61 to tend to ride out of the groove 76.

The material of the wood trim may be solid wood, having an attractivedecorative grain, such as oak. Such woods tend to be strong, andresistive to cracks. However, cutting slots into what is inevitably arather thin profile is bound to lead to an increased risk of cracking,especially during assembly (and dis-assembly, since it is a feature ofthe described trim-attachment system that the trim can be removed, e.gfor the purposes of decorating the wall).

As mentioned, placing the female dovetail form in the (plastic)spline-clip, rather than the wood trim, minimises this increased risk.Still, the designer of the wood trim profile should see to it that anample thickness of the wood material lies over and around the cut slots.Also, the type of wood should be selected in deference to the form orprofile of the particular wood trim, and if a particularly-favouredprofile should require the wood to be rather thin, over and around theslots, a wood that is especially resistant to cracking should beselected for that profile.

Even so, wood and wood products do have a tendency to split and crack,and it is an advantage of the system as described that the wood, thoughslotted, is substantially not subjected to forces which might tend toapply tensile stress to the corners of those slots.

On the other hand, if the material of the trim were, for example,plastic, there would be little point in employing the attachment systemas described herein. Where trim is formed as a plastic extrusion, theextruded profile can readily be formed with intricate re-entrantfeatures of shape, as can the spline-clips, such that really almost anyshape would do to secure the profile. It is mainly because wood is soliable to split and to crack, when subjected to tensile stresses, thatthe system as described, with its avoidance of tensile stresses in theprofile of the trim, is advantageous.

The same shortcoming that wood has, i.e its tendency to split and crack,is present also in many manufactured wood-based materials. Thus,manufactured materials such as particle board, and especially the fibreboards, are, like wood itself, also liable to split and crack ifoverstressed in tension. (Such materials are sometimes used as a basefor trim profiles, often being wrapped with a veneer of a decorativewood). The layered-paper type of wood-like products are, if anything,even more likely to split and crack.

The system as described is most advantageous when used with materialsthat do indeed tend to split and crack if and when subjected to tensilestresses. Materials like (most) plastics and metals, by contrast, tendto stretch and yield when subjected to excessive tensile stress. Theprior art is replete with attachment systems suitable for use with thosenon-crackable materials, which are highly unsuitable for use with woodand wood-based liable-to-split materials.

The system has been described herein as it applies to doors requiringwood trim on both sides, i.e both in the room inside the door, and inthe room outside the door. In some cases, wood trim might only berequired on one side of the door, e.g because the other side of the doorfaces an unfinished room. In that case, the installer should not seek tosecure the jamb to the wall by placing the spline-clips just on the oneside of the door.

One function of the spine clips, as described, is to support the jambrelative to the wall, and if spline-clips were provided just one side ofthe door, the door jamb would not have proper support. So, where it isdesired to apply trim just to one side of the door, still thespline-clips should be provided on both sides of the door; either that,or the jambs (and lintel) could be shimmed in the conventional manner.

Although described for doors, the system can also be used forwindows—especially in cases, again, where wood trim is required bothinside and outside the window. This is not a common situation, however,in that usually the outside of a window is exposed to the elements.

The system can however be used advantageously with outside windows, insome cases. For new installations, the as-manufactured jamb of thewindowframe can be provided with a groove, for receiving a key, e.g thekind of groove as shown in FIGS. 6,7 a,8. FIG. 10 a shows such awindowframe 110, having a groove 112.

It should be understood that the windowframe 110 is already secured intothe opening in the wall, being shimmed and (rigidly) attached to thestud 23, in the conventional manner. FIG. 10 a shows a key 74 enteringthe groove 112, as the jamb-piece 114 is being pressed outwards.

The spline-clip 60 is already secured into its groove in thesplit-jamb-piece 114. When the spline-clip 60 makes contact with thewall surface 116, the installer can then staple the spline-clip 60 tothe wall. After that, it only remains for the installer to assemble andtap home the (already pre-mitred) wood trim onto the spline-clips, andthe installation is finished.

This may be contrasted with what has to be done when wood trim isinstalled around a window in the conventional manner. Windowframes,though square and accurate as to their in-factory manufacture, afterinstallation very rarely reside accurately straight and upright in theopening in the wall. In particular, the distance from the (grooved)inside edge 111 of the windowframe 110 to the inside surface 116 of thewall is not constant around the whole perimeter of the window.

Typically, when conventionally finishing a window, the installer firstattaches jamb-pieces (similar to 114 in FIG. 10 a) to the inside edges111 all around the windowframe 110. These jamb-pieces extend inwards,the installer having seen to it that the pieces are cut so as to projectinwards slightly beyond the wall surface 116. Next, the installer shavesdown the projecting portions of the jamb-pieces 114 until their frontedges are all flush with the inside surface of the wall, all around thewindow. Now, the installer has flat surfaces to which he can attach thewood trim.

By the use of the system as described, the front edges 115 of thesplit-jamb-pieces automatically align themselves flush and straight withthe wall surface 116, simply as a consequence of the spline-clip 60making contact with the wall-surface.

After installation, there will probably be a non-constant gap betweenthe jamb-piece 114 and the windowframe 110. A piece of corner trim 117readily conceals this gap.

The system can also be used with existing windowframes (which do nothave grooves 112), as shown in FIG. 10 b. Here, a separate grooved-strip118 is first attached to the inside edge of the existing windowframe.Now, the jamb-piece 119, again with its spline clips 60 pre-attached toit, is inserted into the groove in the grooved-strip 118 attached to thewindowframe. Installation of the jamb-pieces and spline-clips iscompleted by stapling the spline-clips to the wall, as before. Then, itonly remains for the installer to finish the job by tapping home thepre-mitred wood trim.

It should be understood that this variant of the system, as described inrelation to outside windows, can also be used for outside doors.

A craftsman carrying out the task of applying lengths of baseboardmoulding at the foot of the walls of a room generally finds it a simplematter to apply long straight lengths of baseboard moulding to a longwall. The difficult part of the craftsman's task arises at the corners.Indeed, if it were not for the difficulties posed by the corners, thejob would hardly require the skill and experience that merits the term“craftsman”.

Generally, at the corners of the room, the lengths of baseboard mouldinghave to be mitred together. Alternatively, one of the baseboards can becoped at its end to the profile of the other, but that too is a skill-and time-consuming task. The task of forming perfect mitres and copingsis rendered the more difficult in that corners of rooms in houses arevery rarely perfectly square. The craftsman knows, however, that thehouseholder will not accept that badly-mitred baseboards can be excusedbecause of the difficulties caused by the out-of-squareness of thewalls. The craftsman is expected to produce perfect-looking mitres, inthe baseboard mouldings, whatever the squareness condition of thecorners of the walls of the room.

The degree of out-of-squareness of any one particular room corner is notpredictable. Therefore, it is practically not possible for the mitredjoints to be prepared ahead of time, e.g in a factory. Therefore, itfalls to the craftsman himself, on the job, to assess the degree ofout-of-squareness, and to assess the compensatory compound-angle cutsthat will be required, and generally to determine just how best to matchthe ends of the baseboard mouldings so as to achieve the appearance ofperfectly-mitred joints. And this task falls to the craftsman on thebasis of starting afresh in every single corner of every single room.

FIG. 11 illustrates how the job of applying baseboard mouldings to aroom could be hugely simplified, if only the ends of the baseboardmouldings could be left a little distance short of the (un-square)corner. If FIG. 11 were all that were required, the job of affixingbaseboards could be left to the most inept, casual, unskilled, worker.

In the present case, it will be understood that, as far as thebaseboards themselves are concerned, leaving the baseboards 120,121short, as in FIG. 11, is, indeed, all that is required. The savings inlabour costs—at craftsman rates—will be clearly apparent.

Of course, merely to leave the ends of the baseboards open, anduncovered, as in FIG. 11, is unsightly and unacceptable. FIG. 12 showshow the open ends of the baseboard mouldings may be effectively, andelegantly, concealed. The cover 123 is simply placed and secured intothe corner, over the mouldings.

The cover 123 is shown in detail in FIGS. 13-16. The cover 123 is simplya shell, which has been moulded to fit over the baseboard mouldings120,121. That is to say, the cover 123 is profiled to complement theprofile of the particular baseboard moulding.

Another baseboard moulding profile would require a different profile oftrim. However, this is not particularly onerous in terms of marketingand stock-keeping. A baseboard moulding stockist can only stock so manybaseboard profiles, and it is a simple matter to locate respective boxesof corresponding covers alongside the stocks of the baseboards.

The cover 123 should be quite thin, as to its material thickness.However, it is recognised that, with a cover of the form as illustrated,it is not necessary to make the cover 123 so thin that the coverpractically disappears when placed over the baseboard mouldings 120,121.It is recognised that, so long as the cover is roughly (or exactly) ofthe same appearance and finish as the baseboards themselves, the covermakes a decorative (though not obtrusive) feature of the corner. It isrecognised that, without having to make the cover so thick and chunky asto be obtrusive, the designer has ample scope to specify an adequatethickness for the material of the cover, from the standpoint of strengthand rigidity, without compromising appearance.

It is preferred that the cover be made out of wood, or wood products.Thus, the cover may be formed as a compression moulding, comprising woodchips in an adhesive matrix. Manufactured thus, a thickness of aboutone-and-a-half or two millimetres would give rise to a product havingsufficient strength and resilience as to survive reasonably carefulinstallation. The prudent installer would make sure to provide a numberof spare covers, in case of accidental breakages. (Baseboard mouldingsthemselves are not completely free of the danger of breakage andspoilage, and the installer would provide some spare lengths of that,also.)

As may be seen in FIGS. 13-16, the cover 123 is (inevitably, given itsfunction) of an awkward and fragile-seeming shape. The ability not tohave to skimp on material thickness is important, given that shape.

The visible outer surface of the cover (seen in FIG. 13) can be paintedto match the baseboard. Or, the visible outer surface can be wrappedwith glued-on veneer, again to match the baseboard.

The cover 123 can alternatively be manufactured as a plasticinjection-moulding. Now, the thickness can be reduced, e.g down to aminimum of about one-half millimetre, although one millimetre would bepreferred.

A variant manner of manufacture of the cover, when it is done inplastic, would be as an extrusion. Now, the cover described herein wouldbe formed as a mitred corner comprising two pieces of the extrudedprofile, glued together at a mitred joint. The mitred joint would bemanufactured in-factory, whereby the joint could be perfectly aligned,and could be assured of being stronger than the extruded form itself.

Alternatively again, the cover could be manufactured as a pressing insheet metal, and be thinner still. However, metal is less preferred, inthat it can be difficult to procure a finish, in metal, that has theappearance of wood. That difficulty would not arise if the baseboardswere to be painted, of course. On the other hand, metal ages and settlesdifferently from wood, and a metal cover might be more likely to becomeobtrusive after a time.

As illustrated, the cover 123 is formed with an upper platform 125. Theplatform 125 is provided in order to serve the following function. It isall too common, especially in rooms in which the walls are plastered,for the profile of the intersection of two walls 129,130 to have theform as shown in FIG. 17. That is to say, even though the walls might beapproximately at right angles, there is a bump 132 or bulge orpromontory in one (or both) walls, right at the corner—due to a build-upof plaster in the corner. Such a bump 132 is especially likely to bepresent at the foot of the wall, i.e right where the baseboards 120,121are to be installed. When such a bump is present, the task of producinga neatly-mitred corner joint is especially difficult.

The cover 123, with its platform 125, can ease this difficulty. First,the baseboard mouldings 120,121 are installed into the corner (that isto say, just short of the actual corner, as in FIG. 11). Then, theinstaller assembles the cover into the corner. Now, the bump or bulge132 will prevent the platform from being installed to its full extent.The installer therefore notes which places along the edge of theplatform 125 need to be trimmed back, in order to allow the cover 123 tofit snugly against the wall, around the whole corner.

It is a simple matter for the installer to remove those places on thethin material of the platform 125 of the cover 123 with a trimmingknife, file, etc. In fact, the installer can very quickly learn how totrim the platforms 125 in this manner, and thereby can enable the cover123 to fit reasonably perfectly into the corner, in just a few momentswith a trimming knife or file. FIG. 18 shows how the platform 125 hasbeen trimmed to exactly follow the profile of the bulge or bump 132.

It is also not unheard of for one of the walls at a corner to beindented at the corner, rather than to protrude. To cater for that case,the designer should provide for the platform 125 to overhang the profileof the baseboards, by a couple of millimetres.

As illustrated in FIG. 16, and in the alternative FIG. 16 a, thematerial of the platform 125 itself is rather thinner than the mainprofile of the cover 123. This allows the installer to quickly cut orshave such material from the platform edges as might need to be removed.

FIG. 14 is a pictorial view of the back side of the cover 123, i.e theside that makes contact with the baseboards 120,121. It will beunderstood that the formed profile of the surfaces shown in FIG. 14 is a“negative” of the profile of the visible surface of the baseboards.

Provision for enabling the cover 123 to be adhered to thealready-in-place baseboard mouldings 120,121 takes the form of theadhesive patches 136, as shown. The cover 123 is attached to thebaseboards after the baseboards have been installed on the wall, andtherefore the task of applying (or activating) the adhesive, falls tothe installer. The adhesive patch preferably uses the type of glue thatsticks on contact. Prior to application, the patch 136 is protected by acovering strip, which is removed just before (final) assembly of thecover into the corner, over the baseboards. The designer might specifythe kind of glue that holds the corner-cover firmly to the baseboards,but yet allows the user to remove the corner-cover (by carefully pullingit off) from the baseboards. Some glues also are, upon the corner-coverbeing replaced, capable of re-sticking the corner-cover to thebaseboards.

The designer might also wish to secure the corner-cover to thebaseboards by driving a nail through the corner-cover, and into thestuds of the wall, in the corner. However, this is not preferred, for acouple of reasons:—the nail holes would then have to be filled andfinished; and the driving of the nail might cause distortion of thecorner-cover, or might cause the material of the corner-cover (or of thebaseboard) to split.

Other kinds of adhesive might be preferred. Instead of providinglocalised patches, the designer may prefer to provide adhesive over thewhole area of the back (i.e the area visible in FIG. 14) of the cover.Two-part adhesives can be used, especially of the kind in which the parton the back of the cover is not sticky until activated, and theactivator is in a form that the installer can apply to the face of thebaseboards, just prior to assembly.

In the alternative of FIG. 19, shown in the close-up FIG. 19 a, thecover 138 includes a layer 140 of resilient foam or other compressiblematerial, applied to the back (i.e non-visible) surface of the outercover 141. The outer cover 141 itself can be made of wood products(including solid wood), or plastic, or metal, and finished asappropriate. The layer 140 of soft material is about one millimetrethick or more. The compressible layer 140 assists conformance of theprofile of the cover 138 to the profile of the baseboard 142, even if(slightly) mis-aligned.

Upon assembly of the cover, the thickness of the layer 140 would bevisible between the material of the outer cover 141 and the baseboard142. However, the foam may be suitably coloured, so the layer 140 ispractically invisible—or rather camouflaged—when the cover 138 is inplace. The presence of the layer 140 thus enables the cover to appear tofit perfectly to the baseboards 142,143 even in cases where there mightbe some slight mis-alignment.

The layer 140 is pre-glued inside the wood material of the outer cover141, in-factory. The adhesive by which the layer 140, in turn, isadhered to the baseboards 142,143 is applied to the surface of thematerial of the layer, and again this adhesive is activated by theinstaller.

The covers as previously described were for internal corners. Thedescribed style of structure can also be used for external corners, asillustrated at 149 in FIG. 20. Again, the platform 150 on top of thecover may be quickly trimmed by the installer to conform to the actualshape of the corner 151 of the wall. (External corners of walls are evenmore likely than internal corners to be out of square, especially at thefoot of the wall, where the baseboards 152,153 are located.) The detailsof the form of the external corner cover not shown in FIG. 20 correspondto those of the internal corners.

The two arms or limbs of the corner piece are set at right angles. Thelimbs should be equal in length. (There might be cases where thedesigner might wish to make the two limbs unequal in length, or to setthe limbs at some angle other than a right angle. For example, astockist might wish to make covers with the limbs set at 135° availableas a stock item.

The lengths of the limbs would typically be three cm. Preferably, thelimbs should not be less than about fifteen mm in length, or the covercould hardly be expected to fulfil its function of covering the ends ofthe baseboards; or, even if it did at least cover the ends of thebaseboards, such short limbs might make installation requirous of almostas much craftsmanship as mitring the joints.

The limbs should preferably not be more than about six cm long, becausecovers longer than that would probably be regarded as too obtrusive.That is just an aesthetic aspect, however, since there is no technicalreason why the limbs cannot be longer. The longer the limbs, also, thegreater the possibility that covers in closely adjacent corners mightinterfere with each other.

As noted, one of the aspects of wall construction, in houses, is thatthe very bottoms of the walls tend to be provided with an abundance offilling compound, and to stand slightly proud of the surface of the restof the wall. This is disadvantageous from the standpoint of conventionalbaseboards. If a baseboard were to stand even slightly away from thesurface of the wall, the resulting gap is very noticeable and obtrusive;and a bulge at the foot of the wall has the effect of exacerbating sucha gap between the wall and the top of the baseboard. Conventionalinstallers therefore tend to cut the mitres between baseboards at aslight compound angle, so that the baseboards, at least at the corners,where the problem is likely to be worst, lie with the bottoms of thebaseboards slightly further out from the wall than the tops of thebaseboards. The use of the covers, as described, eliminates this aspect,as a practical problem.

FIG. 21 shows the foot of a wall of a room. The wall surface is formedby a sheet of plasterboard 160, which is screwed to a stud 161, attachedto a sole plate 163, attached to the floor in the conventional manner.Carpet 164 is secured to the floor.

In the baseboard attachment system shown in FIG. 21, the baseboard 165is formed with a slot or groove 167 (FIG. 22). The baseboard has a wallside and a room side 170 (which is visible from within the room), andthe groove 167 is formed in the wall side. The groove 167 in thebaseboard 165 is defined by a wall-facing surface 172 and a room-facingsurface 174.

The system included a hook-clip 176. The hook-clip is formed as anextrusion in plastic, and its extruded profile is shown in FIG. 22. Theprofile includes a flat attachment-element 178, via which the clip isattached to the wall. The attachment-element 178 presents afastener-receiving face when ready for attachment to the wall. Nails,staples 180, etc, can be driven through the attachment element 178,through the plasterboard 160, and into the stud 161 behind.

Above the attachment-element 178, the profile of the hook-clip 176includes a hook-element, comprising a hook 181 and a hook-extender 183.Below the attachment-element 178, the profile of the hook-clip 176includes a buffer-element, comprising a buffer 185 and a buffer-extender187.

The hook-element is springy. The nominal (i.e unstressed) profile of thehook-clip 176, is shown in FIG. 22. Thus, in FIG. 22, the hook 181 ofthe hook-clip is shown interfering with the room-facing surface 174 ofthe baseboard 165. Thus, the hook element is forced, by thecomplementary shape and dimensions of the hook and of the room-facingsurface 174, to bend in the direction into the room, away from the wall.

The surface of the hook 181 is indented, as shown, so that the hook canengage both sides of the groove 167, and not become jammed therebetween.The indentations or ripples mean that the baseboard is retained quitefirmly on the hooks of the hook-clips, against accidental dislodgement,but the baseboard can be lifted off the clips without undue effort.

The buffer-element also is springy. Again, in FIG. 22, the buffer 185 ofthe hook-clip is shown interfering with the wall-facing surface 172 ofthe baseboard 165. Thus, the buffer element is forced, by thecomplementary shape and dimensions of the buffer 185 and of thewall-facing surface 172, to bend in the direction towards the wall.

The forces generated by bending the hook-element and the buffer-elementare reacted against the baseboard 165. Together, the hook-force and thebuffer-force produce a turning moment or couple or torque on thebaseboard, urging the baseboard to rotate in a counter-clockwisedirection. The baseboard 165 is, however, prevented from so rotating bythe engagement of a land 189 against the surface of the plasterboard160.

Thus, the resilience of the hook, and the resilience of the buffer,combine together to urge the baseboard into what can be regarded as avery tight contact between the top edge of the baseboard and the wall.It is recognised that this tight contact is very effective in creating avery good appearance of the baseboard relative to the wall.

With conventional baseboard attachment systems, it is all too common forgaps to appear between the baseboard and the wall. Even though verysmall, these gaps can be unsightly.

Because the force or pressure of the baseboard against the wall is theresult of resilience, the system as described provides some marginwhereby, even if the baseboard should change its position, or its size,slightly, still the top edge of the baseboard is pressed tightly againstthe wall surface.

And, of course, changes can take place in the dimensions of thecomponents. Components of houses settle, dry out, shrink, warp, andundergo many other changes. Most of these are very small, but they canbe enough to make the trim in a room, which appeared perfect when it wasfirst installed, look rather shabby after a few years.

With the attachment system as described, however, such changes can beaccommodated. The system makes it possible for the changes to takeplace, but not to lead to any tiny, but unsightly, gaps. What happens isthat the baseboard rotates slightly (counter-clockwise in FIG. 21),whereby the very top of the baseboard remains pressed firmly against thewall. The change of angle of the baseboard is substantially completelyunnoticeable—by contrast with the described gaps, which, if they occur,can be very obtrusively noticeable.

On the other hand, if the baseboards are indeed allowed to rotate, thetendency is for any mitred joints between adjacent baseboards now tostart to open up, at the bottom. However, combining the hook-clip systemwith the joint covers 123,149, as described, can mask such opening-up ofthe mitres that might result from a slight rotation of the baseboards.

The baseboard 170 is supported as to its height on the wall by thecontact of a nose 190 of the baseboard onto the ledge formed by the hookextender 183. Preferably, the thing that defines the rest position ofthe baseboard should not be the engagement of the top of the hook 181with the end of the groove 167, as that might interfere with the forcearising from the hook element urging the baseboard towards the wall.

The baseboard is assembled over the hook-clips 176 simply by placing thebaseboard flat against the wall, slightly above the clips, and thenlowering the baseboard down until the nose 190 abuts the ledge 183. Thatis the end of the installation process. The chamfer 184 at the entranceto the groove 167 ensures that the hook 181 easily enters the groove.

To remove the baseboards, all that is required is to lift them off. Whenthey are replaced, they immediately adopt the position whereby the topsof the baseboards are pressed firmly against the surface of the wall.This aspect is very convenient when it is desired to re-decorate thewall, either with paint or with a covering such as wallpaper.

The dimensions of the profile of the hook-clip 176 are important. Theclip should be of such dimensions and form as to hold the baseboardfirmly against the wall, so that the baseboard is not dislodged byeveryday impacts thereagainst. The clip should not be so tight that theinstaller might find it difficult to assemble the baseboard over theclip.

The profile of the plastic hook-clip preferably should be between ½ mmand 2 mm thick. The distance apart of the hook element and the bufferelement (as measured between their respective points of contact with thebaseboard) should be between 2 cm and 6 cm. The top of the hook 181should be between 1 cm and 5 cm below the very top of the baseboard.

It will be observed that the foot 192 of the baseboard 160 is nottouching anything. Thus, if a person were to press against the foot ofthe baseboard, the baseboard would rotate—clockwise, in FIG. 21. Whenthe pressure was released, the elements of the clip 176 being resilient,the baseboard would immediately rotate back, until the land 189 was onceagain pressed firmly against the wall.

It will be understood that, if the bottom of the baseboard were to besecured to the wall, that would prevent or impede the very top of thebaseboard from pressing tightly against the wall. Thus, the absence ofrestraint at the bottom of the baseboard is in fact a contributoryfactor regarding the capability of the baseboard to move to rotate andthus to maintain the pressure of the top of the baseboard against thewall.

It is not required that there be no restraint at all, at the bottom ofthe baseboard, but rather that any restraint experienced by the bottomof the baseboard should be small. In the case as shown in FIG. 23, thecarpet 164 has been replaced with tiles 192 (or other hard surfaceflooring). The presence of the carpet 164 meant that whatever gaps theremight be between the bottom of the baseboard and the floor would bemasked by the carpet. The use of tiles instead means that the gaps (ifthere are any—which there usually are) will therefore be visible andapparent. A channel-strip 194 serves to mask the gaps.

The channel-strip 194 exerts only a very small force tending to pressthe bottom of the baseboard against the wall. The profile of thechannel-strip includes a long arm 196 that fits behind the baseboard165, and the channel-strip is secured to the wall by means of staples197 that lie at or near the top of the long arm.

Dimensioned and secured in this manner, the channel-strip really doesnot restrain the bottom of the baseboard from adopting its own positionrelative to the wall. At the same time, the channel-strip effectivelydoes mask any gaps there might be between the bottom of the baseboardand the floor. Of course, the channel-strip is installed on the wallprior to the baseboard being installed. (If the channel-strip 194 wereomitted at the time the baseboard was installed, it could easily be putin later, simply upon lifting the baseboard off the clips 176.)

FIG. 24 shows the clips 176 in the form of individual lengths (e.g fiveto ten cm) of extruded plastic. The task of positioning the clips on thewall at the correct height above the floor can be simplified in themanner as shown in FIG. 24. The installer rests a length of thebaseboard on the floor, close to the wall, and makes a line 198 on thewall, along the top of the resting baseboard. The installer alsoprepares a spacer 200, which is of a width (i.e its height in FIG. 24)that, when the baseboard is set thereon, will position the baseboard sothat the bottom of the baseboard just brushes the carpet 164. Holdingthe spacer 200 against the line on the wall, as shown, and holding theclip against the spacer, the installer then places a couple of staplesthrough the clip and into the wall.

The installer might prefer to locate the clips 176 such that the staplesgo through into the stud 161 behind. Alternatively, the installer mightprefer to locate the clips 176 between the studs such that the staplesgo through only the plasterboard 161.

This can be advantageous for the following reason. It often happens thatplasterboard bends inwards slightly, between the studs. When the clipsare placed between the studs, therefore, the clips can serve to draw thebaseboard and the plasterboard together, in the areas between the studs,where the gaps would otherwise be largest.

The clips can be attached to the plasterboard by means of so-calledexpanding staples, which engage the remote or distal surface of theplasterboard, and thus draw the clip and plasterboard together verystrongly. It may be noted that it is not practical to attach regularbaseboard to plasterboard, between the studs, using expanding staples,because the heads of the staples are visibly highly obtrusive—but theheads are not visible when used on the clips.

FIG. 25 shows the use of an alternative hook-clip 205, shown here inconnection with a chair rail 207 rather than a baseboard. Here, thebuffer-element of the clip has been omitted. Thus, all the neededresilience now has to come from the hook 209 itself.

Now, because there is no buffer, the lower part of the chair rail 207has to touch against something (in this case, against wainscot panels210 attached to the wall) in order to provide a reaction to enable theforces arising from the hook 209 to be exerted upon the chair-rail 207.Particularly in the case of a chair rail, which is generally shorter inheight than a baseboard, there can be enough resilience just in the hookto hold the chair rail firmly against the wall.

Also, there is more reason for wanting the bottom of a chair rail totouch the surface of the wall than there is for wanting the bottom of abaseboard to touch the surface of the wall. And, it should not be ruledout that, in some cases, the designer might be able to omit the bufferin the case also of a baseboard.

FIG. 26 shows the corner-cover 123 now used with baseboards 220,221 thathave been attached to the wall using the system shown in FIG. 21. Thisuse of the corner-covers can be especially advantageous for thefollowing reasons.

The baseboard attachment system illustrated in FIG. 21 is aimed mainlyat ensuring a tight fit between the top of the baseboard and thewall—i.e. at ensuring no gaps appear, even after a period of years,between the top of the baseboard and the wall. This on-going tightcontact at the top of the baseboard is achieved, it can be regarded, atthe expense of allowing the bottom of the baseboard to find its ownposition. That is to say, the springiness of the hook and of the buffercause the baseboard to rock or rotate (slightly), if it needs to, inorder to keep the top of the baseboard tight against the surface of thewall.

This rotation, if it occurs, could cause the mitres at the corners ofconverging pieces of the baseboard to open up, near the bottom of thebaseboards. The designer might regard it as a pity if the excellentvisual effect of the tight fit of the tops of the baseboards were to bemarred by mitres that have cracked open; and fortunately thisall-too-possible condition can be alleviated by using the corner-covers123,149 at the corners, when the baseboards are attached by the FIG. 21system.

In this specification, reference is made to walls having outside andinside surfaces. This is for identification. In the terminology ofsplit-frame window or doorframes, the outside frame is typically thehalf of the frame in which the door or window is actually mounted, whichis usually regarded is being towards the outside of the room. Outsidewith respect to one room is inside with respect to the other room, and,although the terms should be applied consistently, the use of the termsshould not be regarded as being limiting in scope.

1. Procedure for fixing a doorframe or windowframe, termed a frame, inan opening in a wall, the wall have an inside surface and an outsidesurface, and for applying wood trim around the frame, including:providing an inside set of plastic spline-clips, each spline-clip havingthe following characteristics:— the spline-clip has a unitarycross-sectional profile that includes a wall-spline and a jamb-spline,the two splines protruding from a connecting web of the clip; and theweb has a wall-contact surface, and the spline-clip is so structuredthat the wall-contact surface of the web can make touching contact withthe flat surface of the wall; providing the frame as a split-frame,comprising an inside-frame that includes left and right inside-jambs,and a separable outside frame that includes left and rightoutside-jambs, wherein:— the split-frame includes an engageablesplit-guide, which is so structured that, when the split-guide isengaged, the inside-frame is movable relative to the outside-frame,being guided and constrained by the split-guide for relative movementonly towards and away from the outside-frame, being the inside-outsidedirection; the structure of the split-guide is such that theinside-frame can be assembled to the outside-frame, in theinside-outside direction, and when assembled thereto the split-guide iseffective to prevent relative movement between the inside and outsideframes in the left-right and up-down directions; and the outside-framelies assembled into the opening in the wall, and is rigidly fixed to thewall; attaching the inside set of spline-clips to the inside-frame,thereby forming an inside sub-assembly comprising the inside-frame andthe inside spline-clips attached thereto; positioning the insidesub-assembly in the opening in the wall; engaging the split-guide, andmoving the inside sub-assembly towards the outside sub-assembly untilthe respective wall-contact-surfaces of the inside spline-clips lie flatagainst the inside surface of the wall; then driving fasteners throughthe webs of the inside spline-clips, thereby fastening the insidespline-clips and the inside-frame to the wall; and then assembling woodtrim onto the inside spline-clips.
 2. As in claim 1, including, prior toassembling the inside frame into the opening, assembling theoutside-frame into the opening by the following procedure: providing anoutside set of the plastic spline-clips; attaching the outsidespline-clips to the outside-frame, to form an outside sub-assemblycomprising the outside-frame and the outside spline-clips attachedthereto; positioning the outside sub-assembly in the opening in thewall; with the wall-contact-surfaces of the outside spline-clips flatagainst the outside surface of the wall, adjusting the orientation ofthe outside-door-frame until the outside door-frame is aligned squarelywithin the opening; then driving fasteners through the webs of theoutside spline-clips, thereby fastening the outside spline-clips and theoutside-frame to the wall; and then assembling wood trim onto theoutside spline-clips.
 3. As in claim 2, wherein: the outside-frame is adoorframe, and includes a door; and the door is hinged to one of theleft and right inside-jambs, and latched to the other.
 4. As in claim 1,including: providing the wood trim with the following characteristics:—the wood trim has a unitary cross-sectional profile that includes awall-spline-slot and a jamb-spline-slot; the respective proximal wallsof the slots together define a male dovetail form, being of a maximumoverall width DM; the profile includes a wall-land, beyond thewall-spline-slot, for making contact with an outer flat surface of thewall; and the profile includes a jamb-land, beyond the jamb-spline-slot,for making contact with an edge face of a jamb component of the frame;and providing the spline-clips with the following characteristics:— thetwo splines of the spline-clip are so angled relatively, and both soangled relative to the web, as to define a female dovetail shape betweenthe two splines; the two splines converge together, the further awayfrom the web, to a minimum distance apart DF, where DF is smaller thanDM; and the spline-clip is elastically deflectable, to the extent thatthe splines can be separated to the distance DM by the application of aseparating force, and can recover resiliently, without damage, upon theseparating force being no longer applied.
 5. As in claim 1, wherein: theinside-jambs and the outside-jambs have respective edge-faces facingeach other; and providing the engageable split-guide by formingrespective key-grooves formed in the respective edge-faces, andproviding a key which engages both key-grooves.
 6. As in claim 1,including attaching the inside set of spline-clips to the inside-frameby the following procedure: the inside-jambs having respective insideedge-faces lying in substantially the same plane as the inside surfaceof the wall, forming respective inside spline-clip grooves in the insideedge-faces of the inside jambs; providing respective barbed lugs on thewebs of the inside spline-clips, the barbed lugs protruding towards theinside-jambs; engaging the barbed lugs into the spline-clip grooves;designing the lugs on the inside spline-clips to be a tight fit in thespline-clip grooves in the inside jambs, whereby, when the lug ispresent inside the spline-clip groove, the spline-clip is therebysecured firmly to the jamb.
 7. As in claim 1, including: in theleft-right sense, by so moving the sub-assembly that the web of theinside clip moves horizontally over the inside surface of the wall; inthe up-down sense, in that the flat of the web of the inside clip ismovable vertically over the flat inside surface of the wall, whileremaining in contact with that surface;
 8. Combination of wood-trim andspline-clips, wherein: the spline-clips are effective to attach thewood-trim around a door or window installation, being an installationthat includes an opening in a wall; the wall, in respect of across-sectional profile of the opening in the wall, includes parallelopposite outer surfaces, and includes also a jamb-piece; the jamb-piecehas respective outer surfaces which are at least approximately co-planarwith the outer surfaces of the wall; the spline-clips of the combinationare of plastic material, which is capable of being pierced by a pointedfastener such as a staple or nail; each spline-clip is configured asfollows: — the spline-clip is in one piece, which has a profile havingan overall width W; the width W of the spline-clip includes aweb-portion, which is shaped to lie flat against one of the outersurfaces of the wall; the web-portion is shaped to bridge a gap betweenone of the outer surfaces of the wall and the co-planar outer surface ofthe jamb-piece; the web-portion of the spline-clip has a wall-end and ajamb-end; at or near the wall-end of the web, the spline-clip includes aprotruding wall-spline; at or near the jamb-end of the web, thespline-clip includes an protruding jamb-spline; each spline has aninner-side-face, being, in respect of each spline, the face that facesthe other spline; the respective inner-side-faces of the splines on thespline-clip lie spaced apart a distance DC; the inner-side-faces slopeinwards with respect to the web-portion, in such manner that therespective inner-side-faces of the two splines of the spline-cliptogether create a female dovetail form; the distance DC is measuredparallel to the wall, and the female dovetail form is so configured thatthe distance DC decreases in proportion to the spacing of the distanceDC from the wall; the splines have tips, and the minimum value of thedistance DC, termed DC-min, occurs at or near the tips; the wood-trimhas the following characteristics: the wood-trim is made of rigid solidmaterial; the wood-trim has a profile that includes a wall-side face,being a face of the trim that lies against the wall, and is therebyhidden from view, when installed; formed into the wall-side face of thetrim are two spline-slots, being a wall-end spline-slot and a jamb-endspline-slot; the two spline-slots are angled inwards, at anglescorresponding to the respective slopes of the two splines; the twospline-slots in the wood-trim have respective inner-faces, which liespaced apart a distance DT; the two inner-faces slope inwards withrespect to the web-portion, in such manner that the two inner-faces ofthe slots in the wood-trim together create a male dovetail form; thedistance DT is measured parallel to the wall, and the male dovetail formis so configured that the distance DT decreases in proportion to thespacing of the distance DT from the wall; the slots have entry corners,and the maximum magnitude of the distance DT, termed DT-max, occurs ator near the entry-corners; the distance DC-min of the female dovetailform is smaller than the distance DT-max of the male dovetail form; theplastic material of the spline-clip is flexible and pliable enough that,when the splines are forced apart with a force F of such magnitude thatthe minimum distance DC-min between the splines is increased to thedistance DT-max, and then released, the splines spring back resilientlywithout taking a permanent set; and the solid material of the wood-trimis rigid enough that a force of the same magnitude as the force F, whenapplied between the entry-corners, causes substantially no reduction inthe distance DT-min.
 9. As in claim 8, wherein: the distance DT-max ofthe solid material of the trim is greater than the distance DT-minmeasured when the plastic material is unstressed, by an interferencedistance ID millimetres; ID is at least ½ mm.
 10. Procedure for fixing adoorframe or windowframe, termed a frame, in an opening in a wall, andfor applying wood trim around the frame, including: providing wood trimhaving the following characteristics: the wood trim has a unitarycross-sectional trim profile that includes a wall-spline-slot and ajamb-spline-slot; the respective proximal walls of the slots in the trimprofile together define a male dovetail form, being of a maximum overallwidth DM; the trim profile includes a wall-land, beyond thewall-spline-slot, for making contact with a flat surface of the wall;and the profile includes a jamb-land, beyond the jamb-spline-slot, formaking contact with an edge face of a jamb component of the frame;providing an inside set of plastic spline-clips, each having thefollowing characteristics:— the spline-clip has a unitarycross-sectional spline-clip profile that includes a wall-spline and ajamb-spline, the two splines protruding from a web of the spline-clip,which joins the two splines; the web has a wall-contact surface, and thespline-clip is so structured that the wall-contact surface of the webcan make touching contact with the flat surface of the wall; the twosplines are so angled relatively as to define a female dovetail shapebetween the two splines; the two splines converge together, the furtheraway from the web, to a minimum distance apart DF, where DF is smallerthan DM; and the spline-clip is resiliently deflectable, to the extentthat the splines can be separated to the distance DM by the applicationof a separating force, and can recover elastically, without damage, uponthe separating force being no longer applied; making a sub-assembly ofthe frame and the inside set of plastic spline-clip; fixing thespline-clips to the frame, in the sub-assembly; placing the sub-assemblyin the opening; adjusting the position of the sub-assembly in theinside-outside sense relative to the opening in the wall by moving thesub-assembly in the inside-outside direction until the flat of the webof the clip lies in contact with the flat inside surface of the wall;with the web of the spline-clip in contact with the flat wall surface,driving a fastener through the web and into the wall; with thespline-clip attached to the wall, and the two splines of the spline-clipprotruding out from the wall, assembling the wood trim onto thespline-clip by placing one of the grooves in the wood trim over one ofthe splines of the spline-clip; so positioning the wood trim, and soapplying a manual force to the wood trim in the direction towards thewall, that the male dovetail in the wood trim, in moving towards thewall, bends one of the splines outwards relative to the other spline,with such deflection as to enable the male dovetail to enter between thesplines; pressing the wood trim so far towards the wall that theelasticity of the spline-clip causes the spline to move back, over themale dovetail; whereby the splines apply a force to the male dovetailurging the wood trim in the direction towards the wall.
 11. Corner coverapparatus, for covering corners at which two pieces of profiled trimconverge, in combination with the trim, wherein: the trim is of the samecross-sectional trim profile at all points along its length; the trimhas an outside or front face, which is formed with a front face profile;the two pieces of trim converge at an angle A; the corner-cover includestwo limbs, set at the angle A to each other; the two limbs are joinedrigidly together at the apex of the angle A; the limbs have respectiveinside faces, having respective inside face profiles; in respect of eachlimb of the corner-cover:— the inside face profile of the limb is thesame at all points along the length of the limb; the front face profileof the limb is the same at all points along the length of the limb; thelimb is shaped and dimensioned to fit against the trim; and when sofitted, the inside face profile of the limb lies against the front faceprofile of the trim and the front face profile of the limb is visible;and the apparatus includes a fastening means, which is effective to urgethe inside faces of the limbs into contact with the respective frontfaces of the two converging pieces of trim, and thus to attach the coverto both pieces.
 12. As in claim 11, wherein the profile of the trim isso configured that, when the pieces of trim are fitted to convergingwalls, with the lengths of the pieces disposed horizontally along thewalls, the height or vertical dimension of the profile is much greaterthan the thickness or horizontal dimension of the profile.
 13. As inclaim 11, wherein the two limbs of the corner-cover are formed togetheras a unitary structure.
 14. As in claim 11, wherein: in respect of thetwo limbs, the cross-sectional thickness of the limb, being the smallestdistance between the inside face profile and the front face profile ofthe limb, is the same at all points along the length of the limb; andthe cross-sectional thickness of the limb, being the smallest distancebetween the inside face profile and the front face profile of the limb,is at least approximately the same over the whole extent of the faceprofiles.
 15. As in claim 11, wherein the inside face profile of thelimb is formed as an accurate negative of the front face profile of thetrim, in that, when the limb of the corner-cover is placed against thefront face of the limb, the inside face profile of the corner-coverconforms closely to the front face profile of the limb.
 16. As in claim11, wherein, in respect of the two limbs, the front face profile of thelimb conforms at least approximately to the inside face profile of thelimb, to the extent that the visible appearance of the corner-cover,when viewed with the trim, merges unobtrusively with the visibleappearance of the trim.
 17. As in claim 11, wherein the corner-coverapparatus includes an outer cover of relatively hard rigid material onwhich the front face profile is formed, and a lining of relatively soft,flexible, deformable material, such as a foam or sponge material, onwhich the inside-face profile is formed.
 18. As in claim 11, wherein:the fastening means comprises patches of adhesive present on the insidefaces of the limbs of the corner-cover; and the adhesive is protectedwith respective protectors which can be peeled away just before applyingthe corner-cover to the pieces of trim.
 19. As in claim 11, wherein thetrim is one of baseboard trim or chair rail trim.
 20. As in claim 11,wherein the angle A is a right angle, and the lengths of the limbs arebetween three and ten cm.
 21. As in claim 11, wherein a pair of thecorner-covers are configured one to cover an external corner and theother to cover an internal corner.
 22. As in claim 11, wherein: thecorner-cover includes a platform, which is configured to overlie anupwards-facing top surface of the trim; and the platform is of athickness that is thinner than that of the cross-sectional profile ofthe limb, between the front profile and the inside profile.
 23. As inclaim 11, wherein the material of the corner-cover is one of solid wood,or injection-moulded plastic.
 24. System for attaching trim, includingbaseboard trim and chair-rail trim, to a wall of a room, wherein: thesystem includes hook-clips, and includes fasteners whereby thehook-clips can be attached to the wall; the trim is of the samecross-sectional trim profile at all points along its length; thehook-clips are of the same cross-sectional hook-clip profile along theirlengths; the trim profile includes a hook-engaging surface, which facesinto the room; the trim profile includes a wall-facing-surface; thehook-clip profile includes an upstanding hook, having a hook surface,which faces the wall; the hook-clip profile includes a buffer, having abuffer surface, which faces into the room; at least one of the hook orthe buffer is resiliently or elastically deflectable; the system is soconfigured that, when the hook-clips are attached to the wall, the trimcan be attached to the hook-clips by lowering the trim downwards ontothe hook-clips, and can be removed from the hook-clips by lifting thetrim upwards from the hook-clips; the trim profile is so configured, inrelation to the wall and to the hook-clip profile, that when the trim islowered down onto the hook-clips, the trim profile touches the hookprofile at (i) a top-of-trim contact point T, at (ii) a hook contactpoint H, and at (iii) a buffer contact point B, wherein:— the point T isa point on the wall-facing surface of the trim, at or near the top ofthe trim profile, and on the wall, at which forceful contact occurs; thepoint H is a point on the wall-facing hook-face of the hook, and on theroom-facing hook-engaging surface of the trim, at which forceful contactoccurs; and the point B is a point on the wall-facing back surface ofthe trim, and on the room-facing buffer surface of the buffer, at whichforceful contact occurs; the point T lies above the point H, and thepoint B lies below the point H; and the effect of the forceful contactsis such that the said at least one of the hook or the buffer undergoesan elastic deflection.
 25. As in claim 24, wherein: the hook-clipprofile includes a ledge; the trim profile includes a nose; and the noseand the ledge are so located in their respective profiles that the trimcan be lowered down onto the hook-clips until the nose comes to rest onthe ledge.
 26. As in claim 24, wherein: the profile of the trim includesa hook-slot, one side of which comprises the room-facing hook-engagingsurface of the trim profile, and the other side comprises a hook-slotwall-facing surface of the trim profile; the sides of the hook-slot inthe trim profile are substantially parallel; the hook is slightlythicker than the width apart of the sides of the hook-slot, to theextent that the hook interferes with the hook-slot; the surface of thehook is rippled, thereby limiting the interference grip of the hook inthe hook-slot; whereby the interference provides a controlled retentionforce, which resists removal of the trim from the hook-clips.
 27. As inclaim 24, wherein: the profile of the trim is so shaped, as a wholeprofile, that it can be cut in a profile cutting machine; being amachine in which the trim passes through along a work-line, and theprofile is cut by saws or cutters which rotate about respective axes;and each axis forms a right angle to the work-line when viewed fromabove and from the side of the work-line.
 28. As in claim 24, wherein:the profile of the trim and the profile of the hook-clip are soconfigured that, when the trim is assembled to the hook-clips, the trimis capable of rotating or rocking about the hook as a fulcrum; whereby,during installation, when the trim is touching the hook at the point H,and is touching the buffer at the point B, the said elastic deflectionurges the trim profile to rotate, about the hook, in the sense to movethe top of the trim towards the wall; thereby creating the said forcefulcontact between the top of the trim and the wall at the point T.
 29. Asin claim 24, wherein: all the said surfaces are vertical or have asubstantial vertical component; whereby:— forces created by the forcefulcontact at the points T, H, and B are all horizontal or have asubstantial horizontal component; and the horizontal contact force atthe point H is reacted by the sum of the horizontal forces at the pointsT and B.
 30. As in claim 24, wherein each hook-clip is of a unitarystructure, the hook and the buffer being formed together in the profilethereof.
 31. As in claim 24, wherein: the trim profile is relieved atlocations between the contact-points, to the extent that contact withthe wall of the room occurs only at point T, and contact with the bufferoccurs only at point B; the point T is at the very top of the trimprofile, in that substantially no portion of the trim profile protrudesabove the point T; and the point T lies at the junction between anupwards-facing top surface of, and a wall-facing back surface of, theprofile of the trim.
 32. Procedure for attaching an inside jamb-frameand trim to an outside jamb-frame of an existing doorframe or windowframe, by the following procedure: providing a profiled moulding, theprofile of which is formed with an internal angle; where the internalangle is dimensioned to fit over and engage with a corner of an the edgeface of the existing outside-jamb; fixing the profiled moulding to theexisting outside-jamb; where the profile of the profiled mouldingincludes a slot, and where a key engages the slot, and thereby locatesor positions the inside jamb-frame with respect to the profiledmoulding, and thereby with respect to the outside jamb-frame; attachingan inside set of spline-clips to an edge face of the outside frame;positioning the inside frame, with the inside spline-clips attached,such that the inside spline-clips lie flat against the inside wall;driving fasteners through the webs of the inside spline-clips, to securethe inside spline-clips, and thereby the inside jamb-frame, to the wall;then applying wood trim to the inside spline-clips.
 33. As in claim 32wherein the key is separable from the inside jamb-frame.